Substituted phosphinophenoxide-metal complexes for the polymerization of olefins

ABSTRACT

Metal complexes obtainable from a metal precursor of a metal of the 6 th -10 th  groups of the Periodic Table in the oxidation state 0 or +2 and a ligand of the formula I,                    
     where the radicals are defined as follows: 
     R 1 , R 2  and R 4  are hydrogen, C 1 -C 12 -alkyl groups, C 3 -C 12 -cycloalkyl groups, C 6 -C 14 -aryl groups, C 2 -C 12 -alkenyl groups, arylalkyl groups, halogens, silyl groups, C 1 -C 12 -alkoxy groups, C 1 -C 12 -thioether groups or amino groups; 
     R 3  is an α-branched C 3 -C 12 -alkyl group or a substituted or unsubstituted C 3 -C 12 -cycloalkyl group, a C 2 -C 12 -alkenyl group, an arylalkyl group, a halogen, a silyl group, a C 1 -C 12 -alkoxy group, a C 1 -C 12 -thioether group or an amino group; 
     X is oxygen, sulfur, 
     Y is hydrogen or a silyl group, 
     R 5  to R 6  are α-branched C 3 -C 12 -alkyl groups or substituted or unsubstituted C 3 -C 12 -cycloalkyl groups; 
     can be used in free form or immobilized on a solid support for the polymerization of 1-olefins.

Substituted phosphinophenoxide-metal complexes for the polymerization ofolefins.

The present invention relates to novel phosphinophenoxide-metalcomplexes for the polymerization of 1-olefins. The invention furtherrelates to catalysts comprising the novel phosphinophenoxide-metalcomplexes, a process for the polymerization of 1-olefins using the novelcomplexes and also the polymers and moldings obtainable in this way.

The metal complexes are obtainable from a metal precursor of a metal ofthe 6^(th)-10^(th) groups of the Periodic Table in the oxidation state 0or +2 and a ligand of the formula I,

where

R¹, R² and R⁴ are, independently of one another:

hydrogen,

C₁-C₁₂-alkyl,

C₁-C₁₂-alkyl bearing one or more identical or different C₁-C₁₂-alkylgroups, halogens,

C₁-C₁₂-alkoxy groups or C₁-C₁₂-thioether groups as substituents,

C₇-C₂₀-arylalkyl,

C₂-C₁₂-alkenyl,

C₃-C₁₂-cycloalkyl,

C₃-C₁₂-cycloalkyl bearing one or more identical or differentC₁-C₁₂-alkyl groups, halogens,

C₁-C₁₂-alkoxy groups or C₁-C₁₂-thioether groups as substituents,

C₆-C₁₄-aryl,

C₆-C₁₄-aryl bearing one or more identical or different C₁-C₁₂-alkylgroups, halogens,

monohalogenated or polyhalogenated C₁-C₁₂-alkyl groups, C₁-C₁₂-alkoxygroups, silyloxy groups OSiR⁷R⁸R⁹, amino groups NR¹⁰R¹¹ orC₁-C₁₂-thioether groups as substituents,

C₁-C₁₂-alkoxy groups,

C₆-C₁₄-aryloxy groups,

C₁-C₁₂-thioether groups,

silyloxy groups OSiR⁷R⁸R⁹,

halogens

or amino groups NR¹⁰R¹¹;

R³ is selected from among the following groups:

α-branched C₃-C₁₂-alkyl groups,

C₁-C₁₂-alkyl bearing one or more identical or different C₁-C₁₂-alkylgroups, halogens,

C₁-C₁₂-alkoxy groups or C₁-C₁₂-thioether groups as substituents in the αposition,

C₇-C₂₀-arylalkyl,

C₂-C₁₀-alkenyl,

C₃-C₁₀-alkenylalkyl having at least one double bond, where at least oneC—C double bond is conjugated with the aromatic,

C₃-C₁₂-cycloalkyl,

C₆-C₁₄-aryl,

C₆-C₁₄-aryl bearing one or more identical or different C₁-C₁₂-alkylgroups, halogens, monohalogenated or polyhalogenated C₁-C₁₂-alkylgroups, C₁-C₁₂-alkoxy groups, silyloxy groups OSiR⁷R⁸R⁹, amino groupsNR¹⁰R¹¹ or C₁-C₁₂-thioether groups as substituents,

C₁-C₁₂-alkoxy groups,

C₆-C₁₄-aryloxy groups,

C₁-C₁₂-thioether groups,

silyloxy groups OSiR⁷R⁸R⁹,

halogens

and amino groups NR¹⁰R¹¹,

where in each case adjacent radicals R¹ to R⁴ may together form a 5- to8-membered ring;

R⁵ and R⁶ are selected independently from among α-branched C₃-C₁₂-alkylgroups,

C₃-C₁₂-cycloalkyl groups,

C₃-C₁₂-cycloalkyl groups bearing one or more identical or differentC₁-C₁₂-alkyl groups,

halogens, monohalogenated or polyhalogenated

C₁-C₁₂-alkyl groups, C₁-C₁₂-alkoxy groups,

silyloxy groups OSiR⁷R⁸R⁹, amino groups NR¹⁰R¹¹ or C₁-C₁₂-thioethergroups as substituents,

X is oxygen, sulfur, selenium, N—R¹², P—R¹² or AsR¹²,

Y is hydrogen or

an alkali metal cation,

a C₁-C₁₈-alkylacyl anion,

a C₆-C₁₄-arylacyl anion or SiR⁷R⁸R⁹,

R⁷ to R¹² are selected independently from among hydrogen, branched orunbranched C₁-C₆-alkyl groups, benzyl radicals and C₆-C₁₄-aryl groups,where in each case two adjacent radicals R⁷ and R⁸ or R¹⁰ and R¹¹ maytogether form a saturated or unsaturated 5- to 8-membered ring.

Polyolefins are of general importance as materials, for example forproducing films or sheets, fibers or hollow bodies, for example bottles.

New improved processes for preparing polyolefins are therefore of greateconomic importance. The type of catalysts used is particularlyimportant in this respect.

Conventional processes and catalysts such as Ziegler-Natta catalysts(e.g. A. Echte, Lehrbuch der technischen Polymerchemie, VCH, Weinheim,New York, Basle, Cambridge, Tokyo; 1993; pp. 301-3) and metallocenes(e.g. DE-A 30 07 725) frequently have the disadvantage that aluminumalkyls have to be used for activating them. These are extremelysensitive to moisture and to Lewis bases, so that the activity of thecatalysts is greatly reduced by any contaminated monomers. In addition,some aluminum alkyls represent a fire hazard.

The nickel complexes described in WO 96/23010 also have to be activatedby means of aluminum alkyls or Lewis acids based on borane.

U.S. Pat. No. 4,472,522 and U.S. Pat. No. 4,472,525 disclose nickelcomplexes having the structure A,

which can be activated without aluminum alkyl. These are suitable forthe oligomerization of ethylene to give 1-olefins (SHOP process). Thiscompound was converted into derivatives in various ways. Despitevariation of the radicals R (see W. Keim et al., Organometallics 1986,5, 2356-9), it was not possible to produce suitable materials since themolar masses obtained are too low.

Furthermore, U.S. Pat. No. 4,472,525 discloses a catalyst systemcomprising ortho-diethylphosphinophenol A′ orortho-diphenylphosphinophenol A″,

which after reaction with Ni(COD)₂ in situ with ethylene gives linearoligomers, but no polymers which can be used as polymeric materials.

Braunstein et al. attempted to influence the yield and structure bychanging the electron density on the chelating phosphorus.

They used the ortho-phosphinophenol derivative B

(J. Pietsch, P. Braunstein, Y. Chauvin, New J. Chem. 1998, 467). Theproducts of the reaction of ethylene and compound B were likewise linear1-olefins having an average degree of oligomerization of 40.

U.S. Pat. No. 3,635,937 discloses selected Ni complexes, for example B′,

where R=methyl or ethyl and L_(x) may be a 1,5-cyclooctadiene, which areable to polymerize ethylene to polyethylene without activation by analuminum alkyl. The molecular weights M_(w) are, at from about 95,000 to162,000, very attractive, but the activities of 0.73 kg of PE/mol ofNi·h (Example II) are too low for industrial applications.

DE-A 33 36 500 and DE-A 34 45 090 disclose Ni catalysts which can beobtained in situ from a tertiary phosphine, a quinoid compound and anNi(O) compound or a precursor which can readily be reduced to an Ni(O)compound. Although they polymerize ethylene to polyethylene, theirpreparation requires very air- and moisture-sensitive Wittig reagents asprecursors, which is disadvantageous for industrial applications.

In his thesis, U. Jux (U. Jux, Thesis at the University of Greifswald,1996) showed that it is possible to prepare polyethylene using Nicomplexes of the compounds C, C′ and C″ without prior activation bymeans of an aluminum alkyl.

However, the activities of 1.4 kg of PE/mol of Ni·h (compound C), 1.4 kgof PE/mol of Ni·h (compound C′) and 2.1 kg of PE/mol of Ni·h (compoundC″) were still too low for industrial applications.

At the GDCh conference in Munich (Aug. 16-21, 1998, cf. conferenceproceedings, poster B197), further Ni complexes which are likewise ableto polymerize ethylene without prior activation by means of an aluminumalkyl were disclosed. Ligands of the formulae D, D′ and D″ were tested.

These compounds are all triarylphosphinophenols. However, the polymersobtained had molar masses of less than 10,000 g/mol, which is too lowfor practical materials. Ni complexes of thediarylmonoalkylphosphinophenols D′″ and D″″

likewise displayed polymerization activity toward ethylene, but themolar masses were still below 10,000 g/mol and thus too low forapplications as materials.

Finally, secondary phosphinophenol ligands (R⁶ in formula I=H) whichwere reacted with Ni(COD)₂ and produced high molecular weightpolyethylene were disclosed at the abovementioned GDCh conference.However, it was found that the secondary phosphinophenols were extremelysensitive toward the slightest traces of atmospheric oxygen. Our ownexperiments using these metal complex systems displayed poorreproducibility; a number of experiments under apparently identicalconditions gave no polymer at all. In industrial-scale plants, however,it is important to have sufficiently robust catalyst systems.

It is an object of the present invention to provide a metal complexsystem which

is able to polymerize 1-olefins at high activities without activation bymeans of aluminum alkyls;

is sufficiently stable toward atmospheric oxygen to give reproducibleresults and thus be suitable for use in industrial plants, and,furthermore,

gives polyolefins whose molar masses are high enough for them to besuitable for producing films, sheets, fibers or hollow bodies.

We have found that this object is achieved by the metal complexesdescribed at the outset which are obtainable from a metal precursor of ametal of the 6^(th)-10^(th) groups of the Periodic Table in theoxidation state 0 or +2 and a ligand of the formula I and are suitablefor polymerizing 1-olefins to give polymeric materials. Here, the choiceof substituents on the ligand is critical.

In the metal precursors, use is made of metals M of the 6^(th)-10^(th)groups of the Periodic Table of the Elements, for example chromium,manganese, iron, cobalt, nickel and palladium. Preference is given toiron, cobalt, nickel and palladium, particularly preferably nickel.These metals are present in the oxidation state 0 or +2. These metalsare stabilized by ligands.

As ligands of the metal precursors, it is possible to use the unchargedmolecules customarily used in coordination chemistry (cf.Elschenbroich/Salzer, “Einführung in die Organometallchemie”, 3^(rd)Edition, B. G. Teubner Verlag, Stuttgart 1990). Preference is given toaliphatic and aromatic phosphines R_(x)PH_(3−x) and amines R_(x)NH_(3−x)where x=0, 1, 2, 3 and R is selected from the group of radicals definedin more detail under R¹ (see below). However, CO, C₁-C₁₂-alkyl nitrilesor C₆-C₁₄-aryl nitriles, e.g. acetonitrile, propionitrile, butyronitrileor benzonitrile, are also suitable. Further ligands which can be usedare singly or multiply ethylenically unsaturated double bond systemssuch as ethenyl, propenyl, cis-2-butenyl, trans-2-butenyl, cyclohexenyl,norbornenyl, 1,5-cyclooctadienyl ligands (“COD”), 1,6-cyclodecenylligands, 1,5,9-all-trans-cyclododecatrienyl ligands, triphenylphosphineligands and norbornadienyl ligands.

Also suitable are anionic ligands such as halide ions, e.g. fluoride,chloride, bromide or iodide, alkyl anions, e.g. (CH₃)—, (C₂H₅)—,(C₃H₇)—, (n-C₄H₉)—, (tert-C₄H₉)— or (C₆H₁₄)—, allyl anions and benzylanions and also aryl anions, e.g. the phenyl anion.

Particularly preferred ligands are ethene ligands, 1,5-cyclooctadienylligands (“COD”), 1,6-cyclodecenyl ligands,1,5,9-all-trans-cyclododecatrienyl ligands, triphenylphosphine ligandsand also norbornadienyl ligands. In these preferred cases, thecorresponding metal precursor is Ni(C₂H₄)₃, Ni(COD)₂,Ni(1,6-cyclodecadiene)₂, Ni(1,5,9-all-trans-cyclododecatriene)₂,Pd(norbornadiene)Cl₂ and also Ni[P(C₆H₅)₃]₄ and Pd[P(C₆H₅)₃]₄.

Very particular preference is given to Ni(COD)₂.

If the metals M are present in the oxidation state +2, a reducing agenthas to be added to generate the oxidation state 0 in situ. Suitablereducing agents are the compounds customary in organic andorganometallic chemistry. Preferred reducing agents are NaH, KH, complexhydrides such as LiAlH₄, LiBH₄, NaBH₄, Na(CN)BH₃, (isobutyl)₂AlH, alkalimetals such as Na, K or Na/K alloy and H₂. Particular preference isgiven to NaH.

The radicals R¹, R² and R⁴ are, independently of one another:

hydrogen,

C₁-C₁₂-alkyl such as methyl, ethyl, n-propyl, isopropyl, n-butyl,isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, sec-pentyl,neopentyl, 1,2-dimethylpropyl, isoamyl, n-hexyl, isohexyl, sec-hexyl,n-heptyl, isoheptyl, n-octyl, n-nonyl, n-decyl, and n-dodecyl;preferably C₁-C₆-alkyl such as methyl, ethyl, n-propyl, isopropyl,n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl,sec-pentyl, neopentyl, 1,2-dimethylpropyl, isoamyl, n-hexyl, isohexyl,sec-hexyl, particularly preferably C₁-C₄-alkyl such as methyl, ethyl,n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl and tert-butyl;

C₃-C₁₂-cycloalkyl such as cyclopropyl, cyclobutyl, cyclopentyl,cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl, cyclodecyl,cycloundecyl and cyclododecyl; preference is given to cyclopentyl,cyclohexyl and cycloheptyl;

examples of substituted cycloalkyl groups are: 2-methylcyclopentyl,3-methylcyclopentyl, cis-2,4-dimethylcyclopentyl,trans-2,4-dimethylcyclopentyl 2,2,4,4-tetramethylcyclopentyl,2-methylcyclohexyl, 3-methylcyclohexyl, 4-methylcyclohexyl,cis-2,5-dimethylcyclohexyl, trans-2,5-dimethylcyclohexyl,2,2,5,5-tetramethylcyclohexyl, 2-methoxycyclopentyl,2-methoxycyclohexyl, 3-methoxycyclopentyl, 3-methoxycyclohexyl,2-chlorocyclopentyl, 3-chlorocyclopentyl, 2,4-dichlorocyclopentyl,2,2,4,4-tetrachlorocyclopentyl, 2-chlorocyclohexyl, 3-chlorocyclohexyl,4-chlorocyclohexyl, 2,5-dichlorocyclohexyl,2,2,5,5-tetrachlorocyclohexyl, 2-thiomethylcyclopentyl,2-thiomethylcyclohexyl, 3-thiomethylcyclopentyl, 3-thiomethylcyclohexyland further derivatives;

C₇-C₂₀-aralkyl, preferably C₇-C₁₂-phenylalkyl such as benzyl,1-phenethyl, 2-phenethyl, 1-phenylpropyl, 2-phenylpropyl,3-phenylpropyl, neophyl(1-methyl-1-phenylethyl), 1-phenylbutyl,2-phenylbutyl, 3-phenylbutyl and 4-phenylbutyl, particularly preferablybenzyl,

C₂-C₁₂-alkenyl, preferably C₂-C₆-alkenyl such as vinyl, 1-propenyl,isopropenyl, 1-butenyl, isobutenyl, sec-butenyl, buta-1,3-dienyl,n-pent-1-enyl, isopentenyl, sec-pentenyl, neopentenyl, isoprenyl,1,2-dimethylpropenyl, n-hexenyl, isohexenyl, sec-hexenyl, particularlypreferably C₂-C₄-alkenyl such as vinyl, 1-propenyl, isopropenyl,1-butenyl, isobutenyl, sec-butenyl and buta-1,3-dienyl;

C₆-C₁₄-aryl such as phenyl, 1-naphthyl, 2-naphthyl, 1-anthryl,2-anthryl, 9-anthryl, 1-phenanthryl, 2-phenanthryl, 3-phenanthryl,4-phenanthryl and 9-phenanthryl, preferably phenyl, 1-naphthyl and2-naphthyl, particularly preferably phenyl;

C₆-C₁₄-aryl such as phenyl, 1-naphthyl, 2-naphthyl, 1-anthryl,2-anthryl, 9-anthryl, 1-phenanthryl, 2-phenanthryl, 3-phenanthryl,4-phenanthryl and 9-phenanthryl substituted by one or more

C₁-C₁₂-alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl,isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, sec-pentyl,neopentyl, 1,2-dimethylpropyl, isoamyl, n-hexyl, isohexyl, sec-hexyl,n-heptyl, isoheptyl, n-octyl, n-nonyl, n-decyl, and n-dodecyl;preferably C₁-C₆-alkyl such as methyl, ethyl, n-propyl, isopropyl,n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl,sec-pentyl, neopentyl, 1,2-dimethylpropyl, isoamyl, n-hexyl, isohexyl,sec-hexyl, particularly preferably C₁-C₄-alkyl such as methyl, ethyl,n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl and tert-butyl;

halogens such as fluorine, chlorine, bromine and iodine, with preferencebeing given to chlorine and bromine,

monohalogenated or polyhalogenated C₁-C₁₂-alkyl groups such asfluoromethyl, difluoromethyl, trifluoromethyl, chloromethyl,dichloromethyl, trichloromethyl, bromomethyl, dibromomethyl,tribromomethyl, pentafluoroethyl, perfluoropropyl and perfluorobutyl,particularly preferably fluoromethyl, difluoromethyl, trifluoromethyland perfluorobutyl;

C₁-C₁₂-alkoxy groups, preferably C₁-C₆-alkoxy groups such as methoxy,ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, sec-butoxy,tert-butoxy, n-pentoxy, isopentoxy, n-hexoxy and isohexoxy, particularlypreferably methoxy, ethoxy, n-propoxy and n-butoxy;

silyloxy groups OSiR⁷R⁸R⁹ where R⁷ to R⁹ are selected independently fromamong hydrogen, C₁-C₆-alkyl groups, benzyl radicals and C₆-C₁₄-arylgroups; preference is given to the trimethylsilyloxy, triethylsilyloxy,triisopropylsilyloxy, diethylisopropylsilyloxy, dimethylthexlsilyloxy,tert-butyldimethylsilyloxy, tert-butyldiphenylsilyloxy,tribenzylsilyloxy, triphenylsilyloxy and tri-para-xylylsilyloxy groups;particular preference is given to the trimethylsilyloxy group and thetert-butyldimethylsilyloxy group;

or amino groups NR¹⁰R¹¹, where R¹⁰ and R¹¹ are selected independentlyfrom among hydrogen, C₁-C₆-alkyl groups and C₆-C₁₄-aryl groups which mayform a saturated or unsaturated 5-10-membered ring; preference is givento the dimethylamino, diethylamino, diisopropylamino, methylphenylaminoand diphenylamino groups. Examples of amino groups having saturatedrings are the N-piperidyl group and the N-pyrrolidinyl group; examplesof amino groups having unsaturated rings are the N-pyrryl, N-indolyl andN-carbazolyl groups;

C₁-C₁₂-thioether groups such as methylthio, ethylthio, propylthio,1-methylpropylthio, 1,1-dimethylethylthio, phenylthio, 1-naphthylthio,2-naphthylthio, preferably methylthio, ethylthio and phenylthio;

C₁-C₁₂-alkoxy groups, preferably C₁-C₆-alkoxy groups such as methoxy,ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, sec-butoxy,tert-butoxy, n-pentoxy, isopentoxy, n-hexoxy and isohexoxy, particularlypreferably methoxy, ethoxy, n-propoxy and n-butoxy;

C₆-C₁₄-aryloxy groups such as phenoxy, 1-naphthoxy, 2-naphthoxy,1-anthroxy, 2-anthroxy and 9-anthroxy, preferably phenoxy, 1-naphthoxyand 2-naphthoxy, particularly preferably phenoxy,

C₁-C₁₂-thioether groups such as methylthio, ethylthio, propylthio,1-methylpropylthio, 1,1-dimethylethylthio, phenylthio, 1-naphthylthio,2-naphthylthio, preferably methylthio, ethylthio and phenylthio;

silyloxy groups OSiR⁷R⁸R⁹, where R⁷ to R⁹ are selected independentlyfrom among hydrogen, C₁-C₆-alkyl groups, benzyl radicals and C₆-C₁₄-arylgroups; preference is given to the trimethylsilyloxy, triethylsilyloxy,triisopropylsilyloxy, diethylisopropylsilyloxy, dimethylthexlsilyloxy,tert-butyldimethylsilyloxy, tert-butyldiphenylsilyloxy,tribenzylsilyloxy, triphenylsilyloxy and tri-para-xylylsilyloxy groups;particular preference is given to the trimethylsilyloxy group and thetert-butyldimethylsilyloxy group;

halogens such as fluorine, chlorine, bromine and iodine, with preferencebeing given to fluorine and chlorine;

or amino groups NR¹⁰R¹¹, where R¹⁰ and R¹¹ are selected independentlyfrom among hydrogen, C₁-C₆-alkyl groups and C₆-C₁₄-aryl groups, whichmay form a saturated or unsaturated 5-10-membered ring; preference isgiven to the dimethylamino, diethylamino, diisopropylamino,methylphenylamino and diphenylamino groups. Examples of amino groupshaving saturated rings are the N-piperidyl group and the N-pyrrolidinylgroup; examples of amino groups having unsaturated rings are theN-pyrryl, N-indolyl and N-carbazolyl groups.

R¹ and R² may be joined to one another and, together with the carbonatoms of the parent aromatic, form a 5- to 8-membered ring. For example,R¹ and R² can together be: —(CH₂)₃—(trimethylene),—(CH₂)₄—(tetramethylene), —(CH₂)₅—(pentamethylene),—(CH₂)₆—(hexamethylene), —CH₂—CH═CH—, —CH₂—CH═CH—CH₂—, —CH═CH—CH═CH—,—O—CH₂—O—, —O—CH(CH₃)—O—, —CH—(C₆H₅)—O—, —O—CH₂—CH₂—O—, —O—C(CH₃)₂—O—,—N(CH₃)—CH₂—CH₂—N(CH₃)—, —N(CH₃)—CH₂—N(CH₃)— or —O—Si(CH₃)₂—O—.

R³ is selected from among the following groups:

α-branched C₃-C₁₂-alkyl such as isopropyl, isobutyl, tert-butyl,2-pentyl, 3-pentyl, 2-hexyl, 3-hexyl, 2-isopentyl, 3-isopentyl,neopentyl, 1,2-dimethylpropyl, 2-heptyl, 3-heptyl, 2-isoheptyl,3-isoheptyl, 2-octyl, 3-octyl, 2-nonyl, 3-nonyl, 4-nonyl, 1-decyl,2-decyl, 3-decyl, 4-decyl, 2-undecyl, 3-undecyl, 4-undecyl, 5-undecyl,2-dodecyl, 3-dodecyl, 4-dodecyl, 5-dodecyl, preferably α-branchedC₁-C₆-alkyl groups such as isopropyl, isobutyl, tert-butyl, 2-pentyl,3-pentyl, 2-hexyl, 3-hexyl, 2-isopentyl, neopentyl, 1,2-dimethylpropyland 3-isopentyl, particularly preferably isopropyl, isobutyl andtert-butyl;

C₃-C₁₂-cycloalkyl such as cyclopropyl, cyclobutyl, cyclopentyl,cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl, cyclodecyl,cycloundecyl and cyclododecyl; preferably cyclopentyl, cyclohexyl andcycloheptyl;

examples of substituted cycloalkyl groups are: 2-methylcyclopentyl,3-methylcyclopentyl, cis-2,4-dimethylcyclopentyl,trans-2,4-dimethylcyclopentyl 2,2,4,4-tetramethylcyclopentyl,2-methylcyclohexyl, 3-methylcyclohexyl, 4-methylcyclohexyl,cis-2,5-dimethylcyclohexyl, trans-2,5-dimethylcyclohexyl,2,2,5,5-tetramethylcyclohexyl, 2-methoxycyclopentyl,2-methoxycyclohexyl, 3-methoxycyclopentyl, 3-methoxycyclohexyl,2-chlorocyclopentyl, 3-chlorocyclopentyl, 2,4-dichlorocyclopentyl,2,2,4,4-tetrachlorocyclopentyl, 2-chlorocyclohexyl, 3-chlorocyclohexyl,4-chlorocyclohexyl, 2,5-dichlorocyclohexyl,2,2,5,5-tetrachlorocyclohexyl, 2-thiomethylcyclopentyl,2-thiomethylcyclohexyl, 3-thiomethylcyclopentyl or3-thiomethylcyclohexyl;

C₇-C₂₀-aralkyl, preferably C₇-C₁₂-phenylalkyl such as benzyl,1-phenethyl, 2-phenethyl, 1-phenylpropyl, 2-phenylpropyl,3-phenylpropyl, neophyl (1-methyl-1-phenylethyl), 1-phenylbutyl,2-phenylbutyl, 3-phenylbutyl and 4-phenylbutyl, particularly preferablybenzyl;

C₂-C₁₀-alkenyl having at least one double bond conjugated with thearomatic, preferably vinyl, prop-1-enyl, but-1-enyl, isobutenyl,buta-1,3-dienyl, pent-1-enyl, isoprenyl, hex-1-enyl, oct-1-enyl ordec-1-enyl; particularly preferably vinyl, prop-1-enyl, isobutenyl andbuta-1,3-dienyl;

C₆-C₁₄-aryl such as phenyl, 1-naphthyl, 2-naphthyl, 1-anthryl,2-anthryl, 9-anthryl, 1-phenanthryl, 2-phenanthryl, 3-phenanthryl,4-phenanthryl and 9-phenanthryl, preferably phenyl, 1-naphthyl and2-naphthyl, particularly preferably phenyl;

C₆-C₁₄-aryl such as phenyl, 1-naphthyl, 2-naphthyl, 1-anthryl,2-anthryl, 9-anthryl, 1-phenanthryl, 2-phenanthryl, 3-phenanthryl,4-phenanthryl and 9-phenanthryl substituted by one or more

C₁-C₁₂-alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl,isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, sec-pentyl,neopentyl, 1,2-dimethylpropyl, isoamyl, n-hexyl, isohexyl, sec-hexyl,n-heptyl, isoheptyl, n-octyl, n-nonyl, n-decyl, and n-dodecyl;preferably C₁-C₆-alkyl such as methyl, ethyl, n-propyl, isopropyl,n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl,sec-pentyl, neopentyl, 1,2-dimethylpropyl, isoamyl, n-hexyl, isohexyl,sec-hexyl, particularly preferably C₁-C₄-alkyl such as methyl, ethyl,n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl and tert-butyl;

halogens such as fluorine, chlorine, bromine and iodine, with preferencebeing given to fluorine and chlorine,

monohalogenated or polyhalogenated C₁-C₁₂-alkyl groups such asfluoromethyl, difluoromethyl, trifluoromethyl, chloromethyl,dichloromethyl, trichloromethyl, bromomethyl, dibromomethyl,tribromomethyl, pentafluoroethyl, perfluoropropyl and perfluorobutyl,particularly preferably fluoromethyl, difluoromethyl, trifluoromethyland perfluorobutyl;

C₁-C₁₂-alkoxy groups, preferably C₁-C₆-alkoxy groups such as methoxy,ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, sec-butoxy,tert-butoxy, n-pentoxy, isopentoxy, n-hexoxy and isohexoxy, particularlypreferably methoxy, ethoxy, n-propoxy and n-butoxy;

silyloxy groups OSiR⁷R⁸R⁹ where R⁷ to R⁹ are selected independently fromamong hydrogen, C₁-C₆-alkyl groups, benzyl radicals and C₆-C₁₄-arylgroups; preference is given to the trimethylsilyloxy, triethylsilyloxy,triisopropylsilyloxy, diethylisopropylsilyloxy, dimethylthexlsilyloxy,tert-butyldimethylsilyloxy, tert-butyldiphenylsilyloxy,tribenzylsilyloxy, triphenylsilyloxy and tri-para-xylylsilyloxy groups;particular preference is given to the trimethylsilyloxy group and thetert-butyldimethylsilyloxy group;

or amino groups NR¹⁰R¹¹, where R¹⁰ and R¹¹ are selected independentlyfrom among hydrogen, C₁-C₆-alkyl groups, benzyl radicals and C₆-C₁₄-arylgroups, which may form a saturated or unsaturated 5-10-membered ring;preference is given to the dimethylamino, diethylamino,diisopropylamino, methylphenylamino and diphenylamino groups. Examplesof amino groups having saturated rings are the N-piperidyl group and theN-pyrrolidinyl group; examples of amino groups having unsaturated ringsare the N-pyrryl, N-indolyl and N-carbazolyl groups;

C₁-C₁₂-alkoxy groups, preferably C₁-C₆-alkoxy groups such as methoxy,ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, sec-butoxy,tert-butoxy, n-pentoxy, isopentoxy, n-hexoxy and isohexoxy, particularlypreferably methoxy, ethoxy, n-propoxy and n-butoxy;

C₆-C₁₄-aryloxy groups such as phenoxy, 1-naphthoxy, 2-naphthoxy,1-anthroxy, 2-anthroxy and 9-anthroxy, preferably phenoxy, 1-naphthoxyand 2-naphthoxy, particularly preferably phenoxy,

C₁-C₁₂-thioether groups such as methylthio, ethylthio, propylthio,1-methylpropylthio, 1,1-dimethylethylthio, phenylthio, 1-naphthylthio,2-naphthylthio, preferably methylthio, ethylthio and phenylthio;

silyloxy groups OSiR⁷R⁸R⁹, where R⁷ to R⁹ are selected independentlyfrom among hydrogen, C₁-C₆-alkyl groups, benzyl groups and C₆-C₁₄-arylgroups; preference is given to the trimethylsilyloxy, triethylsilyloxy,triisopropylsilyloxy, diethylisopropylsilyloxy, dimethylhexylsilyloxy,tert-butyldimethylsilyloxy, tert-butyldiphenylsilyloxy,tribenzylsilyloxy, triphenylsilyloxy and tri-para-xylylsilyloxy groups;particular preference is given to the trimethylsilyloxy group and thetert-butyldimethylsilyloxy group;

halogens such as fluorine, chlorine, bromine and iodine, with preferencebeing given to fluorine and chlorine;

or amino groups NR¹⁰R¹¹, where R¹⁰ and R¹¹ are selected independentlyfrom among hydrogen, C₁-C₆-alkyl groups, benzyl groups and C₆-C₁₄-arylgroups, which may form a saturated or unsaturated 5-10-membered ring;particular preference is given to the dimethylamino, diethylamino,diisopropylamino, methylphenylamino and diphenylamino groups. Examplesof amino groups having saturated rings are the N-piperidyl group and theN-pyrrolidinyl group; examples of amino groups having unsaturated ringsare the N-pyrryl, N-indolyl and N-carbazolyl groups.

In a preferred embodiment, R³ together with an adjacent radical, i.e. R²or R⁴, forms a 5- to 8-membered ring which may bear furthersubstituents. For example, R³ and R² or R⁴ can together be:—(CH₂)₃—(trimethylene), —(CH₂)₄—(tetramethylene),—(CH₂)₅—(pentamethylene), —(CH₂)₆—(hexamethylene), —CH₂—CH═CH—,—CH₂—CH═CH—CH₂—, —CH═CH—CH═CH—, —O—CH₂—O—, —O—CH(CH₃)—O—, —CH—(C₆H₅)—O—,—O—CH₂—CH₂—O—, —O—C(CH₃)₂—O—, —N(CH₃)—CH₂—CH₂—N(CH₃)—,—N(CH₃)—CH₂—N(CH₃)— or —O—Si(CH₃)₂—O—.

In a particularly preferred embodiment, R³ and R⁴ together form a systemas in the formula Ia.

In this formula, the gruops Z are identical or different and selectedfrom among the following groups:

hydrogen,

halogen such as fluorine, chlorine, bromine and iodine, preferablyfluorine or chlorine;

C₁-C₄-alkyl such as methyl, ethyl, n-propyl, isopropyl, n-butyl,isobutyl, sec-butyl and tert-butyl;

C₁-C₄-alkoxy such as methoxy, ethoxy, n-propoxy, n-butoxy andtert-butoxy, and

n is an integer from 0 to 4.

R⁵ and R⁶ are selected independently from among the following groups:

α-branched C₃-C₁₂-alkyl such as isopropyl, isobutyl, tert-butyl,2-pentyl, 3-pentyl, 2-hexyl, 3-hexyl, 2-isopentyl, 3-isopentyl,neopentyl, 1,2-dimethylpropyl, 2-heptyl, 3-heptyl, 2-isoheptyl,3-isoheptyl, 2-octyl, 3-octyl, 2-nonyl, 3-nonyl, 4-nonyl, 1-decyl,2-decyl, 3-decyl, 4-decyl, 2-undecyl, 3-undecyl, 4-undecyl, 5-undecyl,2-dodecyl, 3-dodecyl, 4-dodecyl, 5-dodecyl, preferably α-branchedC₁-C₆-alkyl groups such as isopropyl, isobutyl, tert-butyl, 2-pentyl,3-pentyl, 2-hexyl, 3-hexyl, 2-isopentyl, neopentyl, 1,2-dimethylpropyland 3-isopentyl, particularly preferably the isopropyl group;

C₃-C₁₂-cycloalkyl such as cyclopropyl, cyclobutyl, cyclopentyl,cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl, cyclodecyl,cycloundecyl and cyclododecyl; preferably cyclopentyl, cyclohexyl andcycloheptyl;

examples of substituted cycloalkyl groups are: 2-methylcyclopentyl,3-methylcyclopentyl, cis-2,4-dimethylcyclopentyl,trans-2,4-dimethylcyclopentyl, 2,2,4,4-tetramethylcyclopentyl,2-methylcyclohexyl, 3-methylcyclohexyl, 4-methylcyclohexyl,cis-2,5-dimethylcyclohexyl, trans-2,5-dimethylcyclohexyl,2,2,5,5-tetramethylcyclohexyl, 2-methoxycyclopentyl,2-methoxycyclohexyl, 3-methoxycyclopentyl, 3-methoxycyclohexyl,2-chlorocyclopentyl, 3-chlorocyclopentyl, 2,4-dichlorocyclopentyl,2,2,4,4-tetrachlorocyclopentyl, 2-chlorocyclohexyl, 3-chlorocyclohexyl,4-chlorocyclohexyl, 2,5-dichlorocyclohexyl,2,2,5,5-tetrachlorocyclohexyl, 2-thiomethylcyclopentyl,2-thiomethylcyclohexyl, 3-thiomethylcyclopentyl, 3-thiomethylcyclohexyland further derivatives.

X is oxygen, sulfur, selenium, N—R¹², P—R¹² or AsR¹². Here, R¹² isselected from among hydrogen, C₁-C₆-alkyl groups, benzyl groups andC₆-C₁₄-aryl groups.

Y is:

hydrogen,

an alkali metal cation such as Li⁺, Na⁺, K⁺, Rb⁺ and Cs⁺, preferably Na⁺and K⁺;

a C₁-C₁₈-alkylacyl anion such as acetate, propionate, n-butyrate,isobutyrate, valerate, capronate, decanoate and stearate; preference isgiven to the C₁-C₆-alkylacyl anions acetate, propionate, n-butyrate andisobutyrate, particularly preferably acetate;

a C₆-C₁₄-arylacyl anion, preferably benzoate, α-naphthoate, β-naphthoateor 9-anthracenecarboxylate, particularly preferably benzoate;

SiR⁷R⁸R⁹, where R⁷ to R⁹ are selected independently from among hydrogen,C₁-C₆-alkyl groups, benzyl groups and C₆-C₁₄-aryl groups; preference isgiven to the trimethylsilyloxy, triethylsilyloxy, triisopropylsilyloxy,diethylisopropylsilyloxy, dimethylthexlsilyloxy,tert-butyldimethylsilyloxy, tert-butyldiphenylsilyloxy,tribenzylsilyloxy, triphenylsilyloxy and tri-para-xylylsilyloxy groups;particular preference is given to the trimethylsilyloxy group and thetert-butyldimethylsilyloxy group.

The synthesis of the ligands can be carried out by methods known per se.A suitable method is described by J. Heinicke, U. Jux, R. Kadyrov and M.He in Heteroatomic Chem. 1997, 8, 383-396, specifically page 393, and byJ. Heinicke, M. He, R. Kadyrov, P. G. Jones in Heteroatomic Chem. 1998,9, 183-193. Further methods are described in T. Rauchfuβ, Inorg. Chem.1977, 16, 2966. Specific ortho-dialkylphosphinocresol syntheses arepublished in J. Heinicke et al., J. Organomet. Chem. 1983, 243, 1, J.Heinicke et al. Chem. Ber. 1996, 129, 1061 and Chem. Ber. 1996, 129,1547.

The preparation of the complexes from the metal precursor and ligand isadvantageously carried out immediately prior to the polymerization.

To prepare the complexes, the ligand of the formula I is mixed with themetal precursor, preferably in a solvent. Suitable solvents are toluene,ethylbenzene, chlorobenzene, dichlorobenzene, ortho-xylene, meta-xylene,para-xylene and mixtures thereof. Furthermore, cyclic ethers such astetrahydrofuran, dioxane or acyclic ethers such as diethyl ether,di-n-butyl ether, diisopropyl ether or 1,2-dimethoxyethane are alsosuitable. Further suitable solvents are ketones such as acetone, methylethyl ketone or diisobutyl ketone, likewise amides such asdimethylformamide or dimethylacetamide. Mixtures of these solvents withone another are also suitable.

Appropriate molar ratios of ligand to metal compound are in the rangefrom 2:1 to 1:5. The range from 1.1:1 to 1:1.1 is preferred.

It is assumed that the complexes of the present invention arepredominantly present as chelate structures as in formula II or IIa orelse are in dimeric or oligomerized form.

In these formulae, the radicals R¹-R⁶ and also M and X are as definedabove; m is selected from among the integers 1, 2 and 3.

The ligand L¹ can be hydrogen or one of the following radicals:

C₁-C₁₂-alkyl such as methyl, ethyl, n-propyl, isopropyl, n-butyl,isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, sec-pentyl,neopentyl, 1,2-dimethylpropyl, isoamyl, n-hexyl, isohexyl, sec-hexyl,n-heptyl, isoheptyl, n-octyl, n-nonyl, n-decyl, and n-dodecyl;preferably C₁-C₆-alkyl such as methyl, ethyl, n-propyl, isopropyl,n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl,sec-pentyl, neopentyl, 1,2-dimethylpropyl, isoamyl, n-hexyl, isohexyl,sec-hexyl, particularly preferably C₁-C₄-alkyl such as methyl, ethyl,n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl and tert-butyl;

C₃-C₁₂-cycloalkyl such as cyclopropyl, cyclobutyl, cyclopentyl,cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl, cyclodecyl,cycloundecyl and cyclododecyl; preference is given to cyclopentyl,cyclohexyl and cycloheptyl;

examples of substituted cycloalkyl groups are: 2-methylcyclopentyl,3-methylcyclopentyl, cis-2,4-dimethylcyclopentyl,trans-2,4-dimethylcyclopentyl, 2,2,4,4-tetramethylcyclopentyl,2-methylcyclohexyl, 3-methylcyclohexyl, 4-methylcyclohexyl,cis-2,5-dimethylcyclohexyl, trans-2,5-dimethylcyclohexyl,2,2,5,5-tetramethylcyclohexyl, 2-methoxycyclopentyl,2-methoxycyclohexyl, 3-methoxycyclopentyl, 3-methoxycyclohexyl,2-chlorocyclopentyl, 3-chlorocyclopentyl, 2,4-dichlorocyclopentyl,2,2,4,4-tetrachlorocyclopentyl, 2-chlorocyclohexyl, 3-chlorocyclohexyl,4-chlorocyclohexyl, 2,5-dichlorocyclohexyl,2,2,5,5-tetrachlorocyclohexyl, 2-thiomethylcyclopentyl,2-thiomethylcyclohexyl, 3-thiomethylcyclopentyl, 3-thiomethylcyclohexyland further derivatives.

As ligand L², use is made of the customary uncharged molecules or anionsused in coordination chemistry (cf. Elschenbroich, Salzer, “Einführungin die Organometallchemie”, 3^(rd) Edition, B. G. Teubner Verlag,Stuttgart 1990). Examples of suitable ligands are:

aliphatic and aromatic phosphines R_(x)PH_(3−x), amines R_(x)NH_(3−x),where R is selected from among the radicals defined under R¹ to R⁴,

CO,

nitriles containing C₁-C₁₂-alkyl or C₆-C₁₄-aryl radicals, for exampleacetonitrile, propionitrile, butyronitrile or benzonitrile, halide ionssuch as fluoride, chloride, bromide or iodide,

allyl anions,

benzyl anions,

aryl anions such as the phenyl anion,

C₁-C₆-alkyl anions such as (CH₃)—, (C₂H₅)—, (C₃H₇)—, (n-C₄H₉)—,(tert-C₄H₉)— or (C₆H₁₄)—;

singly or multiply ethylenically unsaturated double bond systems such asethenyl, propenyl, cis-2-butenyl, trans-2-butenyl, cyclohexenyl,norbornenyl, 1,5-cyclooctadienyl ligands (“COD”), 1,6-cyclodecadienylligands, 1,5,9-all-trans-cyclododecatrienyl ligands or norbornadienylligands.

In a particularly preferred embodiment, the ligands L¹ and L² are linkedto one another via one or more covalent bonds. Examples of such ligandsare the 4-cyclooctenyl ligand, the 5-cyclodecenyl ligand and theall-trans-1,4-cyclododecadienyl ligand.

The polymerization of 1-olefins using the metal complexes of the presentinvention can be carried out in a manner known per se.

Here, the order of addition of the reagents in the polymerization is notcritical. Thus, gaseous monomer can firstly be injected onto the solventor liquid monomer can firstly be metered in, followed by addition of thecatalyst. However, it is also possible firstly to dilute the catalystsolution with further solvent and subsequently to add monomer.

Examples of 1-olefins which are suitable for the polymerization are:ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene,1-decene and 1-eicosene, and also branched olefins such as4-methyl-1-pentene, vinylcyclohexene and vinylcyclohexane as well asstyrene, para-methylstyrene and para-vinylpyridine, with preferencebeing given to ethylene and propylene. Particular preference is given toethylene.

The copolymerization of two 1-olefins can also be carried out using thecatalyst system of the present invention, with the comonomer being ableto be selected from the following groups:

1-Olefins such as ethylene, propylene, 1-butene, 1-pentene, 1-hexene,1-heptene, 1-octene, 1-decene and 1-eicosene, and also branched olefinssuch as 4-methyl-1-pentene, vinylcyclohexene and vinylcyclohexane aswell as styrene, para-methylstyrene and para-vinylpyridine, withpreference being given to propylene, 1-butene, 1-pentene, 1-hexene,1-heptene, 1-octene, 1-decene;

polar monomers such as acrylic acid, C₁-C₆-alkyl acrylates, methacrylicacid, C₁-C₆-alkyl methacrylates, C₁-C₆-alkyl vinyl ethers and vinylacetate; preference is given to methyl acrylate, ethyl acrylate, n-butylacrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate,ethyl vinyl ether and vinyl acetate.

Here, the ratio of the two monomers can be chosen without restriction.

The actual polymerization usually proceeds at a pressure of 1-4000 barand temperatures of 10-250° C., with preference being given to theranges 2-100 bar and 40-150° C.

Suitable solvents are aromatic solvents such as benzene, toluene,ethylbenzene, chlorobenzene, dichlorobenzene, ortho-xylene, meta-xyleneand para-xylene and also mixtures thereof. Further suitable solvents arecyclic ethers such as tetrahydrofuran, dioxane or acyclic ethers such asdiethyl ether, di-n-butyl ether, diisopropyl ether or1,2-dimethoxyethane. Also suitable are ketones such as acetone, methylethyl ketone or diisobutyl ketone, likewise amides such asdimethylformamide or dimethylacetamide. Furthermore, mixtures of thesesolvents with one another as well as mixtures of these solvents withwater or alcohols such as methanol or ethanol are also suitable.

Modern industrial polymerization processes for olefins are suspensionprocesses, bulk polymerization processes in the liquid or supercriticalmonomer and also gas-phase processes. The latter may be stirred gasphase or fluidized-bed gas-phase processes.

In these industrial processes, it is advantageous for catalyticallyactive substances to be immobilized on a solid support. Otherwise,morphology problems with the polymer (lumps, wall deposits, blockages inlines or heat exchangers) can result, forcing shutdown of the plant.

The catalyst system of the present invention can readily be deposited ona solid support without suffering any significant drop in activity.Suitable support materials are, for example, porous metal oxides ofmetals of groups 2-14, for example Mg, Ca, Sr, Ba, B, Al, Ti, Zr, Fe, Znor Si or else mixtures thereof, also sheet silicates as well as solidhalides such as fluorides, chlorides or bromides of metals of groups 1,2 and 13, e.g. Na, K, Mg, Ca or Al. Preferred examples of metal oxidesof groups 2-14 are SiO₂, B₂O₃, Al₂O₃, MgO, CaO and ZnO. Preferred sheetsilicates are montmorrilonites or bentonites; preferred halides areMgCl₂ and amorphous AlF₃.

Particularly preferred support materials are spherical silica gels andaluminosilicate gels of the formula SiO₂·a Al₂O₃, where a is generally anumber in the range from 0 to 2, preferably from 0 to 0.5. Such silicagels are commercially available, e.g. Silica Gel 332 or S 2101 from W.R.Grace.

As particle size of the support material, it has been found to be usefulto employ mean particle diameters in the range 1-300 μm, preferably from20 to 80 μm, with the particle diameter being determined by knownmethods such as sieving. The pore volume of these supports is generallyfrom 1.0 to 3.0 ml/g, preferably from 1.6 to 2.2 ml/g and particularlypreferably from 1.7 to 1.9 ml/g. The BET surface area is 200-750 m²/g,preferably 250-400 m²/g.

To remove impurities, in particular moisture, adhering to the supportmaterial, the support materials can be baked out prior to doping.Temperatures of 45-1000° C. are suitable for this purpose. Temperaturesof 100-750° C. are particularly useful for silica gels and other metaloxides; for MgCl₂ supports, the temperature range 50-100° C. ispreferred. This baking-out should be carried out for a period of from0.5 to 24 hours, preferably from 1 to 12 hours. The pressure conditionsare not critical per se; the baking-out can be carried out atatmospheric pressure. However, reduced pressures of from 0.1 to 500 mbarare advantageous; a range from 1 to 100 mbar is particularlyadvantageous and a range from 2 to 20 mbar is very particularlyadvantageous. Chemical pretreatment of the support material is alsopossible.

However, the metal complex system of the present invention is generallyso insensitive toward impurities that the preliminary heating of thesupport material can be omitted.

The doping of the catalyst is generally carried out by slurrying thesupport material in a suspension medium and combining the suspensionwith the solution of the metal complex system. Here, the volume of thesuspension medium is generally from 1 to 20 times the pore volume of thecatalyst support.

The low water-sensitivity of the metal complex system of the presentinvention also allows it to be used in emulsion polymerizations. Asemulsifiers, it is possible to use anionic, cationic and also nonionicemulsifiers.

Useful nonionic emulsifiers are, for example, ethoxylatedmonoalkylphenols, dialkylphenols and trialkylphenols (EO content: 3-50,alkyl radical: C₄-C₁₂) and ethoxylated fatty alcohols (EO content: 3-80;alkyl radical: C₈-C₃₆). Examples are the Lutensol® products from BASFAG.

Customary anionic emulsifiers are, for example, alkali metal andammonium salts of alkyl sulfates (alkyl radical: C₈-C₁₂), of sulfuricmonoesters of ethoxylated alkanols (EO content: 4-30, alkyl radical:C₁₂-C₁₈) and ethoxylated alkylphenols (EO content: 3-50, alkyl radical:C₄-C₁₂), of alkylsulfonic acids (alkyl radical: C₁₂-C₁₈) and ofalkylarylsulfonic acids (alkyl radical: C₈-C₁₈).

Suitable cationic emulsifiers are, in general, primary, secondary,tertiary or quaternary ammonium salts containing a C₆-C₁₈-alkyl,C₆-C₁₈-aralkyl or heterocyclic radical, alkanolammonium salts,pyridinium salts, imidazolinium salts, oxazolinium salts, morpholiniumsalts, thiazolinium salts and also salts of amine oxides, quinoliniumsalts, isoquinolinium salts, tropylium salts, sulfonium salts andphosphonium salts. Examples which may be mentioned are dodecylammoniumacetate or the corresponding hydrochloride, the chlorides or acetates ofthe various 2-(N,N,N-trimethylammonium)ethylparaffinic acid esters,N-cetylpyridinium chloride, N-laurylpyridinium sulfate and alsoN-cetyl-N,N,N-trimethylammonium bromide,N-dodecyl-N,N,N-trimethylammonium bromide,N,N-distearyl-N,N-dimethylammonium chloride and also the Geminisurfactant N,N′-(lauryldimethyl)ethylenediamine dibromide. Numerousfurther examples may be found in H. Stache, Tensid-Taschenbuch,Carl-Hanser-Verlag, Munich, Vienna, 1981 and in McCutcheon's,Emulsifiers & Detergents, MC Publishing Company, Glen Rock, 1989.

The solid polymers obtained generally have molecular weights of over10,000.

The molding compositions obtained from the polymers are well suited toconversion into films, sheets, waxes or hollow bodies such as bottles,etc. For this purpose, they can be processed by customary methods suchas extrusion, injection molding or pressing and sintering. Wax-likematerials can, for example, be processed by pelletization or extrusionand can be used in typical wax applications.

WORKING EXAMPLES General Procedure

The indicated amounts of ligand and Ni(COD)₂ were each dissolved at 0°C. in 10 ml of the solvent kept under an argon atmosphere. The twosolutions were subsequently mixed, stirred for 10 minutes at 0° C. and afurther 30 minutes at room temperature and subsequently transferred toan autoclave which had been made inert by means of argon. Whilestirring, ethylene was injected until the indicated pressure had beenreached and the temperature was set to that given in Table 1.Polymerization was carried out for 15 hours as indicated in Table 1, andthe autoclave was then vented via a cold trap cooled to −60° C. and thevolatile constituents were removed by flash distillation at 25-30°C./10⁻² mbar. Catalyst residues were subsequently removed by treatmentwith methanolic hydrochloric acid, the polymer was washed with methanoland dried to constant weight at 25-30° C./10⁻² bar.

All experiments were repeated at least once; in the case of slightvariation of the results, the average was calculated.

Ligands

4,6-Di-tert-butyl-2-(diisopropylphosphino)phenol (formula 1)

4,6-Di-tert-butyl-2-(dicyclohexylphosphino)phenol (formula 2)

4-Methoxy-2-dicyclohexylphosphinophenol (formula 3)

4-Fluoro-2-diisopropylphosphinophenol (formula 4)

Example 1

This example was carried out using 41.8 mg (0.12 mmol) of4,6-di-tert-butyl-2-(diisopropylphosphino)phenol (formula 1) as ligandand 35.5 mg (0.12 mmol) of Ni(COD)₂. As solvent for the complexation, 20ml of toluene were used. Polymerization was carried out for 15 hours at80° C. and a pressure of 50 bar. The yield of polymer and analyticaldata for the polymer are shown in Table 1.

Example 2

This example was carried out using 40.3 mg (0.1 mmol) of4,6-di-tert-butyl-2-(dicyclohexylphosphino)phenol (formula 2) as ligandand 27.4 mg (0.1 mmol) of Ni(COD)₂. As solvent for the complexation, 20ml of toluene were used. Polymerization was carried out for 15 hours at100° C. and a pressure of 50 bar. The yield of polymer and analyticaldata for the polymer are shown in Table 1.

Example 3

This example was carried out using 32.0 mg (0.1 mmol) of4-methoxy-2-dicyclohexylphosphinophenol (formula 3) as ligand and 27.5mg (0.1 mmol) of Ni(COD)₂. As solvent for the complexation, 20 ml oftoluene were used. Polymerization was carried out for 15 hours at 100°C. and a pressure of 50 bar. The yield of polymer and analytical datafor the polymer are shown in Table 1.

Example 4

This example was carried out using 22.8 mg (0.1 mmol) of4-fluoro-2-diisopropylphosphinophenol (formula 4) as ligand and 27.4 mg(0.1 mmol) of Ni(COD)₂. As solvent for the complexation, 20 ml oftoluene were used. Polymerization was carried out for 15 hours at 100°C. and a pressure of 50 bar. The yield of polymer and analytical datafor the polymer are shown in Table 1.

COMPARATIVE EXAMPLES Ligands for the Comparative Examples

ortho-Diethylphosphinophenol (formula A′ from U.S. Pat. No. 4,472,525)4-Methyl-2-(phenylisopropylphosphino)phenol (formula C from U. Jux,Thesis, University of Greifswald, 1996)

4-Methyl-2-(phenylisopropylphosphino)phenyl trimethylsilyl ether(formula C′ from U. Jux, Thesis, University of Greifswald, 1996)ortho-Diphenylphosphinophenol (formula C″ from U. Jux, Thesis,University of Greifswald, 1996)

4-Methyl-2-diphenylphosphinophenol (formula D, this and the followingexamples from Poster of M. He, J. Heinicke et al., GDCh Conference,Munich, Poster B197, Aug. 20, 1998)

4-Methoxy-2-diphenylphosphinophenol (formula D′)

4,6-Di-tert-butyl-2-diphenylphosphinophenol (formula D″)

4,6-Di-tert-butyl-2-(phenyl-tert-butylphosphino)phenol (formula

4-Methyl-2-(phenyl-tert-butylphosphino)phenol (formula D″″)

Comparative Example C1

0.55 g (2 mmol) of Ni(COD)₂ in 30 ml of benzene were admixed with 364 mg(2 mmol) of ortho-diethylphosphinophenol (formula A′) and the mixturewas transferred to an autoclave containing an inert gas atmosphere.Ethylene was injected and the autoclave was heated while stirring untila temperature of 70-80° C. had been reached. Polymerization wassubsequently carried out for 16 hours. In the work-up, only smallamounts of oligomers, but no polyethylene, were found.

Comparative Example C2

This experiment was carried out using 56.8 mg (0.22 mmol) of4-methyl-2-(phenylisopropylphosphino)phenol (formula C) as ligand and60.5 mg (0.22 mmol) of Ni(COD)₂. As solvent for the complexation, 20 mlof toluene were used. Polymerization was carried out for 12 hours at120° C. and a pressure of 40 bar. The yield of polymer and analyticaldata for the polymer are shown in Table 1.

Comparative Example C3

This experiment was carried out using 72.6 mg (0.22 mmol) of4-methyl-2-(phenylisopropylphosphino)phenyl trimethylsilyl ether(formula C′) as ligand and 60.5 mg (0.22 mmol) of Ni(COD)₂. As solventfor the complexation, 20 ml of toluene were used. Polymerization wascarried out for 12 hours at 120° C. and a pressure of 40 bar. The yieldof polymer and analytical data for the polymer are shown in Table 1.

Comparative Example C4

This experiment was carried out using 55.6 mg (0.22 mmol) of2-diphenylphosphinophenol (formula C″) as ligand and 55 mg (0.2 mmol) ofNi(COD)₂. As solvent for the complexation, 30 ml of toluene were used.Polymerization was carried out for 15 hours at 100° C. and a pressure of50 bar. The yield of polymer and analytical data for the polymer areshown in Table 1.

Comparative Example C5

This experiment was carried out using 29.2 mg (0.1 mmol) of4-methyl-2-diphenylphosphinophenol (formula D) as ligand and 27.4 mg(0.1 mmol) of Ni(COD)₂. As solvent for the complexation, 20 ml oftoluene were used. Polymerization was carried out for 15 hours at 100°C. and a pressure of 50 bar. The yield of polymer and analytical datafor the polymer are shown in Table 1.

Comparative Example C6

This experiment was carried out using 30.8 mg (0.1 mmol) of4-methoxy-2-diphenylphosphinophenol (formula D′) as ligand and 27.4 mg(0.1 mmol) of Ni(COD)₂. As solvent for the complexation, 20 ml oftoluene were used. Polymerization was carried out for 15 hours at 100°C. and a pressure of 50 bar. The yield of polymer and analytical datafor the polymer are shown in Table 1.

Comparative Example C7

This experiment was carried out using 39.0 mg (0.1 mmol) of4,6-di-tert-butyl-2-diphenylphosphinophenol (formula D″) as ligand and27.5 mg (0.1 mmol) of Ni(COD)₂. As solvent for the complexation, 20 mlof toluene were used. Polymerization was carried out for 15 hours at100° C and a pressure of 50 bar. The yield of polymer and analyticaldata for the polymer are shown in Table 1.

Comparative Example C8

This experiment was carried out using 37.1 mg (0.1 mmol) of4,6-di-tert-butyl-2-(phenyl-tert-butylphosphino)phenol (formula D″′) asligand and 27.5 mg (0.1 mmol) of Ni(COD)₂. As solvent for thecomplexation, 20 ml of toluene were used. Polymerization was carried outfor 15 hours at 100° C. and a pressure of 50 bar. The yield of polymerand analytical data for the polymer are shown in Table 1.

Comparative Example C9

This experiment was carried out using 27.2 mg (0.1 mmol) of4-methyl-2-(phenyl-tert-butylphosphino)phenol (formula D″″) as ligandand 27.5 mg (0.1 mmol) of Ni(COD)₂. As solvent for the complexation, 20ml of toluene were used. Polymerization was carried out for 15 hours at100° C. and a pressure of 50 bar. The yield of polymer and analyticaldata for the polymer are shown in Table 1.

TABLE 1 Polymerization results for Examples 1 to 4 and ComparativeExamples C1-C9

T g of g of Conver- kg PE/mol Ligand R¹ R³ R⁵ R⁶ Y [° C.] polymeroligomers sion Ni · h M.p./° C. M_(w/g) 1 t-Bu t-Bu i-Pr i-Pr H  80 8.0— 54% 4.4 120.6 23,230 2 t-Bu t-Bu Cy Cy H 100 8.3 <<0.1 93.3%   5.5111-114 12,600 3 H OMe Cy Cy H 100 8.5 0.3 63.8%   5.7 128-130 14,768 4H F i-Pr i-Pr H 100 11.8 0.4 79.2%   7.6 125-128 24,690 A′ (C1) H H EtEt H 55-75 — 0.2 3.5%  0 — — C (C2) H Me Ph i-Pr H 120 3.6 — 41% 1.4n.d. n.d. C′ (C3) H OMe Ph i-Pr SiMe₃ 120 3.6 0.6 48% 1.4 121     9310C″ (C4) H H Ph Ph H 100 6.4 0.2 53% 2.1 117-123   5510 D (C5) H Me Ph PhH 100 9.2 0.3 78% 6.1 116-123   5600 D′ (C6) H OMe Ph Ph H 100 12.8 0.489% 8.5 115-118   4600 D″ (C7) t-Bu t-Bu Ph Ph H 100 6.5 0.1 56% 4.3119-125   8110 D″′ t-Bu t-Bu t-Bu Ph H 100 14.4 0.2 96% 9.6 120-126  5682 (C8) D″″ H Me t-Bu Ph H 100 11.9 0.2 88% 7.9 114-117   5807 (C9)Abbreviations for the radicals: Me = methyl, Et = ethyl, i-Pr =isopropyl, t-Bu = tert-butyl; Cy = cyclohexyl, Ph = phenyl, OMe =methoxy, SiMe₃ = trimethylsilyl.

We claim:
 1. A metal complex obtainable from a metal precursor of ametal of the 6^(th)-10^(th) groups of the Periodic Table in theoxidation state 0 or +2 and a ligand of the formula I,

where R¹, R² and R⁴ are, independently of one another: hydrogen,C₁-C₁₂-alkyl, C₁-C₁₂-alkyl bearing one or more identical or differentC₁-C₁₂-alkyl groups, halogens, C₁-C₁₂-alkoxy groups or C₁-C₁₂-thioethergroups as substituents, C₇-C₂₀-arylalkyl, C₂-C₁₂-alkenyl,C₃-C₁₂-cycloalkyl, C₃-C₁₂-cycloalkyl bearing one or more identical ordifferent C₁-C₁₂-alkyl groups, halogens, C₁-C₁₂-alkoxy groups orC₁-C₁₂-thioether groups as substituents, C₆-C₁₄-aryl, C₆-C₁₄-arylbearing one or more identical or different C₁-C₁₂-alkyl groups,halogens, monohalogenated or polyhalogenated C₁-C₁₂-alkyl groups,C₁-C₁₂-alkoxy groups, silyloxy groups OSiR⁷R⁸R⁹, amino groups NR¹⁰R¹¹ orC₁-C₁₂-thioether groups as substituents, C₁-C₁₂-alkoxy groups,C₆-C₁₄-aryloxy groups, C₁-C₁₂-thioether groups, silyloxy groupsOSiR⁷R⁸R⁹, halogens or amino groups NR¹⁰R¹¹; R³ is selected from amongthe following groups: α-branched C₃-C₁₂-alkyl groups, C₁-C₁₂-alkylbearing one or more identical or different C₁-C₁₂-alkyl groups,halogens, C₁-C₁₂-alkoxy groups or C₁-C₁₂-thioether groups assubstituents in the α position, C₇-C₂₀-arylalkyl, C₂-C₁₀-alkenyl,C₃-C₁₀-alkenylalkyl having at least one double bond, where at least oneC—C double bond is conjugated with the aromatic, C₃-C₁₂-cycloalkyl,C₆-C₁₄-aryl, C₆-C₁₄-aryl bearing one or more identical or differentC₁-C₁₂-alkyl groups, halogens, monohalogenated or polyhalogenatedC₁-C₁₂-alkyl groups, C₁-C₁₂-alkoxy groups, silyloxy groups OSiR⁷R⁸R⁹,amino groups NR¹⁰R¹¹ or C₁-C₁₂-thioether groups as substituents,C₁-C₁₂-alkoxy groups, C₆-C₁₄-aryloxy groups, C₁-C₁₂-thioether groups,silyloxy groups OSiR⁷R⁸R⁹, halogens and amino groups NR¹⁰R¹¹, where ineach case adjacent radicals R¹ to R⁴ may together form a 5- to8-membered ring; R⁵ and R⁶ are selected independently from amongα-branched C₃-C₁₂-alkyl groups, C₃-C₁₂-cycloalkyl groups,C₃-C₁₂-cycloalkyl groups bearing one or more identical or differentC₁-C₁₂-alkyl groups, halogens, monohalogenated or polyhalogenatedC₁-C₁₂-alkyl groups, C₁-C₁₂-alkoxy groups, silyloxy groups OSiR⁷R⁸R⁹,amino groups NR¹⁰R¹¹ or C₁-C₁₂-thioether groups as substituents, X isoxygen, sulfur, selenium, N—R¹², P—R¹² or AsR¹², Y is hydrogen or analkali metal cation, a C₁-C₁₈-alkylacyl anion, a C₆-C₁₄-arylacyl anionor SiR⁷R⁸R⁹, R⁷ to R¹² are selected independently from among hydrogen,branched or unbranched C₁-C₆-alkyl groups, benzyl radicals andC₆-C₁₄-aryl groups, where in each case two adjacent radicals R⁷ and R⁸or R¹⁰ and R¹¹ may together form a saturated or unsaturated 5- to8-membered ring.
 2. A metal complex as claimed in claim 1, obtainablefrom a metal precursor of a metal M selected from the group consistingof iron, cobalt or nickel in the oxidation state 0 or palladium in theoxidation state 0 or +2, where the ligand or ligands of the metalprecursor are selected from the group consisting of the followingligands: ethylenically unsaturated double bond systems, phosphinesR_(x)PH³⁻¹ amines R_(x)NH_(3−x), CO, nitriles, halide ions, C₁-C₆-alkylanions, allyl anions, benzyl anions and aryl anions, where R is selectedfrom among hydrogen, C₁-C₆-alkyl groups and C₆-C₁₄-aryl groups, x is 0,1, 2 or 3; and a ligand of the formula I in which R¹, R² and R⁴ are,independently of one another: hydrogen, C₁-C₆-alkyl, C₁-C₆-alkyl bearingone or more identical or different C₁-C₆-alkyl groups, halogens,C₁-C₆-alkoxy groups or C₁-C₆-thioether groups as substituents,C₇-C₂₀-arylalkyl, C₂-C₆-alkenyl, C₅-C₇-cycloalkyl, C₅-C₇-cycloalkyl,bearing one or more identical or different C₁-C₆-alkyl groups, halogens,C₁-C₆-alkoxy groups or C₁-C₆-thioether groups as substituents,C₆-C₁₄-aryl, C₆-C₁₄-aryl, bearing one or more identical or differentC₁-C₆-alkyl groups, halogens, monohalogenated or polyhalogenatedC₁-C₆-alkyl groups, C₁-C₆-alkoxy groups, silyloxy groups OSiR⁷R⁸R⁹,amino groups NR¹⁰R¹¹ or C₁-C₆-thioether groups as substituents,C₁-C₆-alkoxy groups, C₆-C₁₄-aryloxy groups, C₁-C₆-thioether groups,silyloxy groups OSiR⁷R⁸R⁹, halogens or amino groups NR¹⁰R¹¹; R³ isselected from among the following groups: α-branched C₃-C₆-alkyl groups,C₁-C₆-alkyl, bearing one or more identical or different halogens,C₁-C₆-alkoxy groups or C₁-C₆-thioether groups as substituents in theα-position, C₇-C₂₀-arylalkyl, C₂-C₁₀-alkenyl, C₃-C₁₀-alkenylalkyl havingat least one double bond conjugated with the aromatic, C₅-C₇-cycloalkyl,C₅-C₇-cycloalkyl, bearing one or more identical or different C₁-C₆-alkylgroups, halogens, C₁-C₆-alkoxy groups or C₁-C₆-thioether groups assubstituents, C₆-C₁₄-aryl, C₆-C₁₄-aryl bearing one or more identical ordifferent C₁-C₆-alkyl groups, halogens, monohalogenated orpolyhalogenated C₁-C₆-alkyl groups, C₁-C₆-alkoxy groups, silyloxy groupsOSiR⁷R⁸R⁹, amino groups NR¹⁰R¹¹ or C₁-C₆-thioether groups assubstituents, C₁-C₆-alkoxy groups, C₆-C₁₄-aryloxy groups,C₁-C₆-thioethet groups, silyloxy groups OSiR⁷R⁸R⁹, halogens and aminogroups NR¹⁰R¹¹, where in each case adjacent radicals R¹ to R⁴ maytogether form a 5- to 8-membered ring; R⁵ and R⁶ are selectedindependently from among α-branched C₃-C₆-alkyl groups, C₅-C₇-cycloalkylgroups, C₅-C₇-cycloalkyl groups bearing one or more identical ordifferent C₁-C₁₂-alkyl groups, halogens, monohalogenated orpolyhalogenated C₁-C₆-alkyl groups, C₁-C₆-alkoxy groups, silyloxy groupsOSiR⁷R⁸R⁹, amino groups NR¹⁰R¹¹ or C₁-C₆-thioether groups assubstituents, benzyl radicals, X is oxygen or sulfur, Y is hydrogen oran alkali metal cation, a C₁-C₃-alkylacyl anion, a C₆-C₁₄-arylacyl anionor SiR⁷R⁸R⁹, R⁷ to R¹¹ are selected independently from among hydrogen,C₁-C₆-alkyl groups, benzyl radicals and C₆-C₁₄-aryl groups, where ineach case two adjacent radicals R⁷ and R⁸ or R¹⁰ and R¹¹ may togetherform a saturated or unsaturated 5-8-membered ring.
 3. A metal complex asclaimed in claim 1, obtainable from a metal precursor selected fromamong the compounds Ni(C₂H₄)₃, Ni(1,5-cyclooctadiene)₂,Ni(1,6-cyclodecadienene)₂, Ni(1,5,9-all-trans-cyclododecatriene)₂,Pd(norbornadiene)Cl₂, Ni[P(C₆H₅)₃]₄ and Pd[P(C₆H₅)₃]₄, and a ligand ofthe formula I in which R¹, R² and R⁴ are, independently of one another:hydrogen, C₁-C₄-alkyl, C₁-C₄-alkyl bearing one or more identical ordifferent C₁-C₄-alkyl groups, halogens, C₁-C₄-alkoxy groups orC₁-C₄-thioether groups as substituents, benzyl, C₂-C₄-alkenyl,C₅-C₇-cycloalkyl, phenyl, phenyl bearing one or more identical ordifferent C₁-C₄-alkyl groups, halogens, monohalogenated orpolyhalogenated C₁-C₄-alkyl groups, C₁-C₄-alkoxy groups or silyloxygroups OSiR⁷R⁸R⁹ as substituents, C₁-C₄-alkoxy groups, phenoxy,C₁-C₄-thioether groups, silyloxy groups OSiR⁷R⁸R⁹, halogen, or aminogroups NR¹⁰OR¹¹; R³ is selected from among the following groups:α-branched C₃-C₆-alkyl groups, C₁-C₄-alkyl bearing one or more identicalor different halogens or C₁-C₄-alkoxy groups as substituents in the αposition, benzyl, C₅-C₇-cycloalkyl, phenyl, phenyl bearing one or moreidentical or different C₁-C₄-alkyl groups, halogens, monohalogenated orpolyhalogenated C₁-C₄-alkyl groups, C₁-C₄-alkoxy groups, silyloxy groupsOSiR⁷R⁸R⁹ or amino groups NR¹⁰R¹¹ as substituents, C₁-C₄-alkoxy groups,phenoxy, C₁-C₄-thioether groups, silyloxy groups OSiR⁷R⁸R⁹, halogens andamino groups NR¹⁰R¹¹, where in each case adjacent radicals R¹ to R⁴ maytogether form a 5- to 8-membered ring; R⁵ and R⁶ are selectedindependently from among α-branched C₃-C₆-alkyl groups andC₅-C₇-cycloalkyl groups, X is oxygen or sulfur, Y is hydrogen or analkali metal cation, a C₁-C₃-alkylacyl anion, a benzo cation orSiR⁷R⁸R⁹, where R⁷ to R⁹ are selected independently from among hydrogen,C₁-C₄-alkyl groups and phenyl groups; R⁷ to R¹¹ are selectedindependently from among hydrogen, C₁-C₄-alkyl groups and phenyl groups,where in each case two adjacent radicals R⁷ and R⁸ or R¹⁰ and R11 maytogether form a saturated or unsaturated 5- to 8-membered ring.
 4. Ametal complex as claimed in claim 1, obtainable fromNi(1,5-dicyclooctadienyl)₂ and a ligand of the formula I in which R¹, R²and R⁴ are, independently of one another: hydrogen, C₁-C₄-alkyl, benzyl,C₅-C₇-cycloalkyl, phenyl, phenyl bearing one or more identical ordifferent C₁-C₄-alkyl groups, halogens, monohalogenated orpolyhalogenated C₁-C₄-alkyl groups, C₁-C₄-alkoxy groups or silyloxygroups OSiR⁷R⁸R⁹ as substituents, C₁-C₄-alkoxy groups, phenoxy,C₁-C₄-thioether groups, silyloxy groups OSiR⁷R⁸R⁹, or halogen; R³ isselected from among the following groups: α-branched C₃-C₆-alkyl groups,C₁-C₄-alkyl bearing one or more identical or different halogens orC₁-C₄-alkoxy groups as substituents in the a position, benzyl,C₅-C₇-cycloalkyl, phenyl, phenyl bearing one or more identical ordifferent C₁-C₄-alkyl groups, halogens, monohalogenated orpolyhalogenated C₁-C₄-alkyl groups, C₁-C₄-alkoxy groups or silyloxygroups OSiR⁷R⁸R⁹ as substituents, C₁-C₄-alkoxy groups, phenoxy,C₁-C₄-thioether groups, silyloxy groups OSiR⁷R⁸R⁹, halogens and aminogroups NR¹⁰R¹¹, where in each case adjacent radicals R¹ to R⁴ maytogether form a 5- to 8-membered ring; R⁵ and R⁶ are selectedindependently from among α-branched C₃-C₆-alkyl groups andC₅-C₇-cycloalkyl groups, R⁷ to R¹¹ are selected independently from amonghydrogen, C₁-C₄-alkyl groups and phenyl groups, where in each case twoadjacent radicals R⁷ and R⁸ or R¹⁰ and R¹¹ may together form a saturatedor unsaturated 5- to 8-membered ring, X is oxygen or sulfur and Y ishydrogen.
 5. A metal complex as claimed in claim 1, obtainable fromNi(1,5-dicyclooctadienyl)₂ and a ligand of the formula Ia,

where R¹ and R² are, independently of one another: hydrogen,C₁-C₄-alkyl, branched or unbranched, benzyl, C₅-C₇-cycloalkyl, phenyl,phenyl bearing one or more identical or different C₁-C₄-alkyl groups,halogens, monohalogenated or polyhalogenated C₁-C₄-alkyl groups,C₁-C₄-alkoxy groups or silyloxy groups OSiR⁷R⁸R⁹ as substituents,C₁-C₄-alkoxy groups, phenoxy, C₁-C₄-thioether groups, silyloxy groupsOSiR⁷R⁸R⁹ or halogen; R⁵ and R⁶ are selected independently from amongα-branched C₃-C₁₂-alkyl groups and C₅-C₇-cycloalkyl groups, R⁷ to R¹¹are selected independently from among hydrogen, C₁-C₄-alkyl groups andphenyl groups, where in each case two adjacent radicals R⁷ to R¹¹ maytogether form a saturated or unsaturated 5-8-membered ring, Z isselected from among halogen, C₁-C₄-alkoxy and C₁-C₄-thioether groups; Xis oxygen or sulfur and Y is hydrogen.
 6. A catalyst for thepolymerization of 1-olefins, comprising the metal complex defined inclaim 1 immobilized on a solid support material.
 7. The catalyst definedin claim 6, wherein the solid support material is selected from thegroup consisting of porous metal oxides, sheet silicates and solidhalides.
 8. A process for the polymerization of 1-olefins, whichcomprises bringing the metal complex defined in claim 1 into contactwith one or more 1-olefins at a pressure of 1-1000 bar and a temperatureof 10-250° C., and wherein the metal complex is optionally immobilizedon a solid support material.
 9. The process of claim 8, which isconducted at a pressure of 2-100 bar and a temperature of 40-150° C. 10.The process of claim 8, wherein the 1-olefin is ethylene.
 11. Theprocess of claim 8, wherein the metal complex is immobilized and thesolid support material is selected from the group consisting of porousmetal oxides, sheet silicates and solid halides.
 12. The process ofclaim 9, wherein the metal complex is immobilized and the solid supportmaterial is selected from the group consisting of porous metal oxides,sheet silicates and solid halides.
 13. The process of claim 9, whereinthe 1-olefin is ethylene.
 14. The process of claim 10, wherein the metalcomplex is immobilized and the solid support material is selected fromthe group consisting of porous metal oxides, sheet silicates and solidhalides.